MICROSTRUCTURE AND TENSILE PROPERTIES OF SQUEEZE CAST Mg-Al-Ca ALLOYS

Microstructure and tensile properties of squeeze cast Mg-Al-Ca alloys with different levels of calcium addition (AMC50X) were studied. The microstructural analysis by optical and scanning electron microscopy (SEM) shows that the squzeeze cast Mg-Al-Ca alloys contain primary alpha-Mg, (Al, Mg)(2)Ca and Mn-Al intermetallic while the base alloy AM50 contains primary alpha-Mg, beta-Mg12Al17 and Mn-Al intermetallic. The addition of calcium varying from 1 to 4 wt.% increases the fraction area of Ca-containing secondary phases from 9.5% to 19.5%. The experimental observation confirms also that the calcium has a grain refining effect on the base alloy AM50A. The tensile testing results indicate that, as the calcium content of AMC50X alloys increases from 0 to 4%, the ultimate tensile strength (UTS) and elongation (E-f) decrease dramatically at room temperature as their yield strengths (YS) improves slightly. At 150 degrees C, however, both the UTS and YS of the alloys increase with increasing the Ca content.